Conventionally, a known parking assist system displays, on a display device, an image representing an external environment around a vehicle. A parking target position that corresponds to a target position where the vehicle is to be parked is superimposed on the image representing the external environment around the vehicle. According to technology employed in the known parking assist system (for example, JP2005-67566A which will be hereinafter referred to as Patent reference 1), in a case where movement, for example, a backward movement, of the vehicle is detected after the parking target position is set, a moving amount of the vehicle is calculated, and the parking target position is corrected in accordance with the calculated moving amount and then a corrected set target parking position is displayed on the display device.
However, according to the technology of the known parking assist system of Patent reference 1, the moving amount of the vehicle is calculated and the parking target position is corrected only after the parking target position is set. Accordingly, in a case where, for example, a parking-possible region is periodically detected as the parking target position and the detected parking target position is displayed on the display device sequentially before the parking target position is set by the parking assist system and/or a driver, due to a delay in a processing of displaying the parking target position, the displayed parking target position differs from an actual parking target position because the vehicle has moved during a period of time from the detection of the parking-possible region to the display of the parking target position. Thus, a difference or mismatch between the displayed parking target position and the actual parking target position occurs.
A need thus exists for a parking assist apparatus, a parking assist method and a computer readable medium including a program thereof, which is not susceptible to the drawback mentioned above.